1. From the Department of Physiology (F.R.G., V.V.L., F.S.C., R.C.W., R.C.T.) and Vascular Biology Center (J.C.S., D.M.P.), Medical College of Georgia, Augusta, Ga; Department of Pharmacology (F.R.G., V.V.L., F.S.C., Z.B.F., M.H.C.C., R.C.T.), Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil.